Tnsberg 2930 2004

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SAND CLEANING STATFJORD C FIELD TEST
Stavanger 18 19 January 2006 Henrik Dannström,
MATOR AS
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CURRENT PRACTICE ON THE NORWEGIAN SHELF

• Solids are normally handled in dedicated
  treatment units.
• In most cases jetting water and associated solids
  are treated separate from main produced water
  stream.
• Solids are reinjected, treated to achieve
  discharge quality or sent onshore for disposal.

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BACKGROUND

• Discharge quality governed by
• REGULATIONS RELATING TO CONDUCT OF ACTIVITIES IN
  THE PETROLEUM ACTIVITIES (THE ACTIVITIES
  REGULATIONS)
• Section 59 discharge of cuttings, sand and solid
  particles
• Cuttings from drilling and well activities, sand
  and other solid particles shall not be discharged
  to sea if the oil content of formation oil, other
  oil or base fluid in organic drilling fluid is
  more than ten grams per kilogram of dry matter.
• Dedicated sand treatment not available on
  Statfjord C. Statoil therefore wanted in 2005 to
  investigate sand treatment methods utilising
  existing equipment (Flash Tank CD2015).

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CONCEPT STAGES

• Theoretical evaluation
• optional cleaning methods (mechanical, steam,
  chemical)
• suitability of CD2015 for selected method
  (pressure, temperature, materials,
  instrumentation etc)
• sampling and analysing methods
• ? Decision to investigate condensate wash
• Laboratory test
• washing of sand with condensate
• ? Decision to proceed with field test

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TEST SET-UP, PILOT SCALE
Process and test separator jetting water and
sand routed batchwise in to CD2015. Excess
water drained between jettings.
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TEST CONDITIONS, PILOT SCALE

• Volumetric flow rate to ensure fluidisation of
  sand in one of three jetting sections
• Fluidisation factor (F) to be higher than 0.0011)

1) Tippets, R Priestman G Liquid Jet
Fluidisation and Solids Wash Out
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TEST CONDITIONS, PILOT SCALE

• Operating pressure to ensure liquid phase
  condensate in wash section

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TEST CONDITIONS, PILOT SCALE

• Mixing of condensate and sand / water
• - inline mixer used
• Condensate flow rate to fit purpose
• tested with 0.1 0.2 vol- of water flow rate
• Recirculation
• - until desired oil-on-sand concentration
  achieved
• Disposal of hydrocarbons
• - flashing / disposal through flare and skimming
  to reclaimed oil sump

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TEST SET-UP, PILOT SCALE
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ANALYZING METHODS

• Sampling
• Concentration and analysis
• Filtering 1.2 µm / 5.0 µm
• Weighing (correction for OiW) washing
  re-weighing
• Method accurate down to 0.2 wt.
• Method to be modified for floating installations
• Retorte accuracy down to 0.5 1.0 wt,
  requires larger sample volumes
• IR / Infracal for OiW

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TEST RESULTS, PILOT SCALE
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TEST RESULTS, PILOT SCALE
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TEST RESULTS, PILOT SCALE

• POSITIVE
• Promising results in terms of cleaning
  efficiency, although 10 g/kg not was achieved
• CD2015 well suited for purpose
• Full scale test may easily be carried out based
  on same principle

• NEGATIVE
• Mechanical failure (leakage) led to modifications
  on site and reduced capacity
• Reduced sand concentration over time

CONCLUSION Results promising enough to proceed
with full scale field test
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TEST SET-UP, FULL SCALE

• Major changes to pilot test
• all three jetting sections utilised
• larger flow rate (larger pump, hoses, lines,
  valves)
• more instrumentation
• longer test period
• more analysing equipment

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TEST SET-UP, FULL SCALE
Pump 210 m3/h 10 barg
Condensate feed to in-line mixer
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TEST CONDITIONS, FULL SCALE

• Volumetric flow rate to ensure fluidisation of
  all sand in vessel
• Tie-in such that all water and sand in vessel are
  circulated
• Operating pressure to ensure liquid phase
  condensate in wash section
• Mixing of condensate and sand / water. In-line
  mixer used.
• Water level 50 - 70 of vessel height
• Condensate flow rate to fit purpose
• Recirculation
• Disposal of hydrocarbons

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TEST RESULTS, FULL SCALE
Results from 1st sand batch circulation
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TEST RESULTS, FULL SCALE
Results from 2nd sand batch circulation
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TEST RESULTS, FULL SCALE
Results from flow regime test
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TEST RESULTS, FULL SCALE

• SUMMARY
• Demonstrated ability to achieve discharge quality
  for oil wetted sand by means of condensate
  washing.
• Associated water quality well below discharge
  requirements.
• Overall condensate consumption to achieve
  cleaning of 1 week of accumulated jetting solids
  approximately 1 m3, of which 20 - 30 reclaimed.

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BATCH PROCESS REQUIREMENTS

• Vessel with holding capacity for separator /
  process vessel jetting inventory
• Pumparound system for vessel inventory, with pump
  discharge pressure above condensate flash point
• Flow capacity and internal distribution
  arrangement to ensure fluidisation of solids
• Suitable mixer and choke
• Condensate with appropriate qualities
• Means for discharge of flashed and gravity
  separated hydrocarbons

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CONCLUSION
Client objective of finding alternative means of
solids treatment identified. Concept is oil
extraction from sand using condensate. This can
be achieved in several configurations. One batch
configuration found suitable for Statfjord
C. Technology qualification next step towards
implementation as permanent installation. Impleme
ntation of concept on other facilities subject to
feasibility evaluation.